The invention concerns a manual control device for executing functions, particularly of an electronic watch. The watch may be, for example, an analogue watch that includes, in a case closed by a crystal, a watch movement powered by an energy source, a dial and hands for indicating the time, and at least one liquid crystal display for displaying data. The device includes a determined number of sensors, one touch sensitive pad of each sensor being arranged on an internal or external face of the watch crystal. In order to control the execution of functions, each sensor can be activated by a user's finger placed on the crystal in a determined zone of the corresponding sensitive pad of the sensor. An electronic circuit receives the signals from each sensor to carry out the specific instruction of an activated sensor.
The invention also concerns an electronic watch which includes such a manual control device for executing functions.
The execution of functions of the watch concerns for example data entry, particularly for composing notes, addresses for an address book, for diary meetings, or for adjusting the time and the date. Moreover, it may also concern functions for modifying or removing stored data, for consulting various menus or stored data, time slots to be programmed, alarms or wireless data transmission.
Within this horological field, multiple embodiments of devices with touch sensitive glass of the capacitive or resistive type have already been proposed, particularly for data entry. Patent Document No. EP 0 791 868 in the name of the Applicant, which concerns a data entry device for an electronic watch, may be cited in this respect. The device includes a keyboard with keys each associated with a sensitive pad of a capacitive type sensor, which is arranged on an inner face of the crystal. Each sensor is intended to control the entry of an item of data associated with the corresponding key when a user's finger is placed on the crystal in a determined zone of the sensitive pad of the sensor to be activated. The transparent sensitive pads of the sensors are distributed inside a contour which is delimited by the watch crystal, for example twenty or so sensitive pads. They can form two crowns and a sensitive pad at the centre.
Since the number of sensitive pads is relatively large, it is proposed to offset the sensitive pads towards the bottom of the crystal in order to correct the visual perception of the user when he wishes to place a finger on a determined sensor. In order to do this, the sensitive pads of an upper part are larger than the sensitive pads of a lower part of the watch crystal.
One drawback of the solution described in European Patent document No. 0 791 868 is that it is difficult to place a finger on a single sensitive pad of a sensor to be activated without influencing neighbouring pads, since a large number of sensitive pads are distributed on the inner face of the crystal. The sensitive pads are not in direct contact with each other, but are separated by a short distance much smaller than the dimension of each pad. Thus, even when the sensitive pads on the crystal are offset, manipulation of such a device requires certain dexterity, which makes data entry difficult.
Another drawback of the solution described in this European Patent document is that each sensor is only intended to enter a single data item namely one character, one figure, one symbol or one operator, which limits the field of application of such a device.
In European Patent document No. 0 838 737, device for identifying a manual action on a surface of a watch crystal is disclosed. Several capacitive type sensors each having a transparent sensitive pad arranged on an inner face of the crystal are used. All the sensitive pads are close to each other and distributed along two crowns and a sensitive pad at the centre. This sensor arrangement, connected to an electronic circuit, allows recognition of a character or a symbol drawn by a finger on the surface of the crystal.
As for the preceding document, one drawback of the solution described in European Patent document No. 0 838 737 is that a significant number of sensitive pads separated by a short distance is arranged on the inner face of the crystal. This means that the device has to be provided with a high-performance electronic circuit intended to detect the sensor having the largest capacitive value from among all the sensors capable of being activated by a user's finger. Consequently, the capacitive value of each sensor has to be measured precisely so as to recognise the character drawn by the finger on the crystal.
It is to be noted that, unlike the present invention, the device for identifying a manual action of this document is not used for executing various functions controlled by the activation of at least one sensor of the set of sensors.